In recent years, graphical interfaces (GUIs) have become common because of widespread use of liquid crystal panels. Until now, GUIs, which have been used only in powerful computers and so on, are gradually spreading into built-in appliances. This is because the use of GUIs has advantages of suppressing an increase in number of switches or the like due to the advanced features of built-in appliances, allowing the user to operate the appliances without difficulty, and so on. This trend may persist in the future too.
However, arithmetic processors such as microcomputers, with low processing power have still been used in the built-in devices from the viewpoint of cost-effectiveness, heat generation, and power consumption. A GUI processing requires a large number of instructions and consumes most CPU resources, affecting the performance of an original application program, such as the delay of start-up thereof. There are strict requirements for the built-in devices and this trend may persist in the future too.
To address such a problem, it has been proposed that part of a software process is replaced with a logic circuit using FPGA to reduce the CPU resource consumption (see, for example, Patent Document 1). The logic circuit performs a process without decoding of instructions. Thus, the logic circuit can effectively performs the process at a high speed, compared with one carried out by the software.
Other methods have been also proposed. In these methods, part of a drawing processing is replaced with a dedicated hardware in the unit of drawing instructions such as “line drawing” and “color calculation”. These methods have been commercialized under the name of “graphic accelerators” (see, for example, Patent Document 2).
Nowadays, furthermore, while it becomes difficult to operate appliances such as air-conditioning appliance and household electrical appliance by some buttons thereon because of the multi-functionality of the appliances, graphical user interfaces allow manufacturers to manufacture appliances that satisfy both multi-functionality and usability. In addition, the operability of the graphical user interfaces allows users to use the basic functions of the appliances without difficulty and also the applied functions thereof. Thus, the operability of the graphical user interfaces leads to enhanced convenience of the users. However, from the viewpoint of manufacturing cost, the display devices of these appliances have significant limitations on the display contents to a liquid crystal and the operating device thereof. In recent years, so-called soft keys have been effective alternatives to input buttons assigned to particular operations, such as “START/STOP” and “WARMING”. The soft key, however, is dynamically assigned to any of functions brought up on the screen. In this case, the more the representation on the screen nears the “soft key” button, the more intuitively a user operates the appliance. In fact, however, the screen and the button are distant from each other in most cases because of the restricted configuration of a liquid crystal display unit.
To realize intuitive operation, for example, a method using magnetism has been proposed in documents, such as Patent Document 3.